A capacitor is a passive two-terminal electrical component used to store energy electro-statically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator). Capacitors are widely used as parts of electrical circuits in many common electrical devices. For example, capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, but can also be used to store data states, such as in a dynamic random access memory (DRAM) device.
For integrated circuits and for DRAM devices in particular, the use of metal-insulator-metal (MIM) capacitors has become widespread in recent years.